let title = document.querySelectorAll('.title li');
let content = document.querySelectorAll('.content li');
console.log(title);

title.forEach(function(item,index){
    item.onclick = function(){
        title.forEach(function(item){
            item.className = '';
        })
        this.className = 'active';

        content.forEach(function(item){
            item.className = '';
        })
        content[index].className = 'show';
    }
})